连江鱼类群落多样性及其与环境因子的关系

Relationship between fish community diversity and environmental factors in the Lianjiang River,Guangdong,China

目前连江梯级开发至12级,为了解梯级开发后连江鱼类群落状况,于2009年3月和2010年4月对连江上、中、下游7个代表江段的鱼类群落结构以及环境因子分别进行了调查,共采集鱼类98种,分属于9目20科75属。海南墨头鱼Garra pingi hainanensis、南方长须鳅鮀Gobiobtia longibarba meridionalis为连江新纪录种。银鮈Squalidus argentatus、黄颡鱼Pelteobagrus fulvidraco、小鳈Sarcocheilichthys parvus、马口鱼Opsariichthys bidens、餐Hemiculter lecuisculus等小型鱼类在鱼类群落结构中占优势地位。对鱼类群落进行聚类分析(CLUSTER)和非度量多维标度排序(NMDS)分析结果表明连江鱼类被划分为3个类群,即下游河口类群、中下游类群及中上游类群;S2、S3两个站位鱼类物种多样性(H')、丰富度(D')和均匀度(J')均高于其他站位。通过对连江各站位鱼类群落与环境因子的典型对应分析发现:河宽、温度、海拔、pH值和水坝之间的距离5个因子与鱼类群落相关性较强(P<0.05)。与历史资料对比后发现,连江鱼类种类、分布、生态类型都发生了巨大变化。

Twelve dams have been constructed along the Lianjlang River during the last 50 years. The fish community structure in this region was documented by collecting fish and measuring environmental indices at seven representative sites in the Lianjiang River between 2009-2010. A total of 98 species were collected, belonging to 9 orders, 20 families, and 75 genera. Among these, Garra pingi hainanensis and Gobiobotia Ionggibarba meridionalis have not previously been documented in the Lianjiang River. Small species, including Squalidus argentatus, Pelteobagrus fulvidraco, Sarcocheilichthys parvus, Opsariichthys bidens, and Hemiculter lecuisculus dominated the local community. The spatial pattern describing the fish community was analyzed using hierarchical and non-metric multidimensional scaling. The fish community of Lianjiang River separated into three clusters： mid-upriver, mid-downriver, and downriver. Group I was located in the mid-upriver, a region characterized by large numbers of cavities and gravel, ideal habitat for resident fish.However, migratory fish are unable to reach this section of the river ＇because of dams located further downstream. Group Ⅱ was located in the mid-downriver reach, in which habitat was similar to the mid-upriver reach. However, it is possible for some migratory fish to pass the two downstream dams and occupy this section of the river. Group Ⅲ was located in the Feilaixia reservoir, which was characterized by deep water and a lack of cavities and gravel. This region of the river was also occupied by a number of migratory fish species. The fish diversity （＇H＇） , species richness （D＇）, and evenness （J＇） at sites S2 and S3 was higher than at the other sites, while the fish diversity （H＇） and species richness （D＇） were lowest at S1. The relationship between the fish community at each site and environmental factors, including channel width, water depth, velocity, dissolved oxygen, transparency, conductance, pH, total dissolved solids, water temperature, elevation, distance between two dams, and riparian cover was analyzed by canonical correspondence analysis. Fish community structure was correlated with river width, water temperature, height, pH, and the distance between two dams （P〈0.05）. Water temperature was played a large role in determining the distribution of fish species, while and also varied with elevation. The water temperature varied considerably between the upriver and downriver reaches of the Lianjiang River. Clearly, the presence of barriers to migration had a significant influence of the distribution of fish species. The width and the distance between two dams was correlated with the area in which fish could migrate. Water pH is influenced by mining along the Lianjiang River and can have a large effect on the growth and reproduction of fish, Based on a comparison with historical data, the fish species assemblage, distribution, and ecotypes in Lianjiang River have changed significantly